This only confirms that cone diameter is a factor in fs, not that it is the determining factor. When comparing drivers with the same motor, yes bolting a larger diameter cone to it will lower fs. But when the motor was designed, any reasonable fs could have been the target goal. This is how we can have 6" subwoofers, or 15" fullrange speakers.

I was just trying to make a general point. Just take any sub in the same series, like DD, Fi, DC, AQ, etc (with the same coils and drivers) and watch the Fs go down. The only factor is cone size, that's what I be sayin' yo.

06-13-2011

audioholic

Re: what does size matter of the sub?

Quote:

Originally Posted by Buck

Lol just taking an educated guess.

MMS is a big factor for higher freqs (its a huge factor in tweeters for example). But for subwoofers, basically speaking, the electro-magnetic motor force potential is the dominant factor. Modern subwoofers have such strong motors that the relatively slight changes in moving mass from one cone to another really are an insignificant factor.

06-13-2011

audioholic

Re: what does size matter of the sub?

Quote:

Originally Posted by Buck

I was just trying to make a general point. Just take any sub in the same series, like DD, Fi, DC, AQ, etc (with the same coils and drivers) and watch the Fs go down. The only factor is cone size, that's what I be sayin' yo.

Yes, I know, I understand. I thought I addressed that above. But this discussion is about cone size, not comparisons of a specific model of sub in its different sizes. So within the context of this discussion, comparing fs specs of same-model drivers to extrapolate that logic to all comparisons creates a false conclusion.

Hope you dont think Im picking on you here Buck, most of what you've said in this thread is correct. I just felt I should point out a couple thing you said that needed clarifying imo.

06-13-2011

Buck

Re: what does size matter of the sub?

Quote:

Originally Posted by audioholic

MMS is a big factor for higher freqs (its a huge factor in tweeters for example). But for subwoofers, basically speaking, the electro-magnetic motor force potential is the dominant factor. Modern subwoofers have such strong motors that the relatively slight changes in moving mass from one cone to another really are an insignificant factor.

I see.

06-13-2011

audioholic

Re: what does size matter of the sub?

Quote:

Originally Posted by Buck

I see.

I should alter what I said there, slightly. Its not only the sheer strength of modern sub motors that minimizes the importance of a few grams difference from one cone assembly to another, its also the fact that they move relatively slowly. MMS is a bigger factor in tweeters not only because they have less powerful motors, but because they are required to move much faster than a subwoofer. 80 cycles per second versus 20,000 cycles per second. At 20,000 stops and starts per second, yeah, moving mass becomes a huge factor.

Hope Im making sense here, Ive had a few beers at this point.

06-13-2011

Buck

Re: what does size matter of the sub?

That's crystal clear to me.

I like for my subs to make 30 cycles and below :)

06-13-2011

JL Audio

Re: what does size matter of the sub?

i have nothing to add to this thread but I will say it got very interesting reading between audio and buck lol. I like threads like this.

06-13-2011

Buck

Re: what does size matter of the sub?

I don't feel picked on, I don't know everything.

06-13-2011

05fronty

Re: what does size matter of the sub?

Quote:

Originally Posted by lowriderram_95

lulz at some of the responses

this

06-13-2011

Seehafer27

Re: what does size matter of the sub?

i agree with you quick, easy and to the point. thanks.

06-13-2011

pro-rabbit

Re: what does size matter of the sub?

Quote:

Originally Posted by 05fronty

this

I was thinking the same thing then Audio posted fixing the situation.

Audio you are a walking text book for mobile electronics, lol.

06-13-2011

VWBobby

Re: what does size matter of the sub?

One point that someone touched on that was not emphasized enough....THERE'S NO REPLACEMENT FOR DISPLACEMENT.
This applies mostly to SPL applications, not SQ.

Displacement can be in the form of cone area x excursion. Displacement can simply be a 21" woofer with a 10mm xmax, or a 8" woofer with 20mm of xmax. If you don't have a lot of cone area, excursion is your friend. Subs like the SA-8, RLI-8, possibly the new Alpine 8" all have a high amount of excursion, thus displacing a lot more air compared to a lower 8".
Cone area can be a good band aid for displacement (if there is a lack of excursion). Lots of cheap 12" subs in a wall, for instance.

SQ: Generally a speaker with a lower Fs, lower moving mass, and well designed/linear motor will sound "better". A sub with a stiffer suspension, higher Fs, and higher moving mass will generally not sound very good, but may be awesome for SPL. This requires having high amounts of power and strong motor force to overcome the suspension stiffness, while not being very accurate/SQ.

Want to instantly win any SPL comp? Line the vehicle with as much cone area and power as it can handle. POP ;)

06-14-2011

audioholic

Re: what does size matter of the sub?

A stiff suspension does not mean distortion will automatically be higher. In fact, a stiffer suspension means once the cone direction is suppose to reverse, the suspension is applying more force to stop its current motion, and reverse it back towards its center position (helps 'cone control', doesnt hurt it). In other words, a stiffer suspension provides more cone damping.

Excursion is only a direct replacement for cone area if the sub displays linear BL throughout its excursion range. For a sub with a standard non Bl optimized motor design, you are generally better off with more cone area than with more excursion.

06-15-2011

FtheNutHuggers

Re: what does size matter of the sub?

DD has a PA version of the 2500 series. It is an 18". It has a higher Fs than the 10" standard version. (just a stir stick for generalizations above)